Wet 3-D printing of epoxy cross-linked chitosan/carbon microtube composite

Over the last decays, the use of conductive biopolymer composites has been growing in areas such as biosensors, soft robotics, and wound dressing applications. They are generally soft hydrophilic materials with good elastic recovery and compatible with biological environments. However, their application and removal from the host are still challenging mainly due to poor mechanical strength. This work displays a technique for the fabrication of complex-shaped conductive structures with improved mechanical strength by wet three-dimensional (3-D) printing, which uses a coagulation bath to quickly solidify an epoxy cross-linked chitosan/carbon microtube composite ink. The fabricated conductive structure demonstrated higher elongation strength and improved elastic stability upon the introducing of polypropylene glycol diglycidyl ether (PPGDGE) as the epoxy cross-linker, which can be due to the formation of networks between oxiran groups of PPGDGE and chitosan amino groups.